The present invention relates to apparatus for terminating a plurality of subterranean cables at the entrance to a cable manhole formed of concrete and buried beneath the surface. Such manholes, though designed to be water resistant, eventually do develop leaks, typically in the wall through which the cables enter. In the replacement of such manhole walls, it is highly desireable to maintain the cables entering the manhole in position and in service. In manhole reconstruction the old wall is destroyed and the cable is temporarily supported by a combination of frameworks and wires between the manhole appearances and the splice box. Thereafter a new wall is constructed in place of the old wall. The sections of cable between manholes are protected by sections of split duct positioned about the cables. The split duct must be terminated at the new wall. According to the present invention, the split duct terminator modules are assembled about the cables in modular units and are thereafter joined together by a solvent cement. A coagulated mass is then formed within the framework constructed from the modules to permeate the entire structure of the interfacing split duct terminator modules. The structure formed receives the split duct sleeves positioned about the cables as they enter the manhole. This allows a new wall to be constructed about the cables without disconnecting the cables or otherwise interrupting service in them.
A very substantial part of the electrical communication network operated and owned by telephone and telegraph companies exists in the form of subterranean electrical signal cables lying beneath the ground. These subterranean cables each contain a great number of message conductors and are interconnected at central offices spaced at periodic intervals. Between the central offices, manholes are provided at intervals determined by the length of cable which can be conveniently and economically wound onto a reel. Access to the manholes is provided for purposes of maintenance, servicing and inspection. Between the manholes, sections of split duct are laid end to end in trenches and cables are drawn through the duct sections. The subterranean manholes are typically formed of concrete and are designed for permanent installation. However, over the years, shifting of the earth about the manholes, soil subsidence, temperature changes, and the formation of ice in crevices in the structure of the manholes all operate to cause damage to the manhole structure. The most frequent form of damage caused by these effects is degradation of service resulting from water leakage in the manholes. For these and other reasons, it is desirable to replace cracked, damaged, and otherwise substandard manholes by building upon the old structure to provide new water resistant manholes.
Because of the requirement for making manholes as water resistant as possible it has been necessary to develop a means of recasting a manhole wall without disconnecting from service or moving the cables that enter the manhole. The split duct terminator of this invention provides such a means.
As an incident of replacement, it is also frequently desireable to expand the area of the manhole both to allow sufficient room for ease of movement by individuals replacing the manhole so as to minimize the risk of damage to the cables appearing therein as well as to accommodate additional conduits or amplifier or repeater equipment which may be desired.
Extreme caution is required in order to replace a manhole without interrupting the service in the communications lines passing through it. Since the number of communications circuits accommodated by a single pair of wires has multiplied over the years, the disruption of communications which would result from the severance of a single cable containing a number of electrical connector pairs is very substantial.